This invention relates to the baling of cotton. More particularly, this invention relates to a cotton baling press and packaging techniques associated therewith.
In the conventional packaging of cotton, the fiber is dumped into a bale box from a feed system which is periodically interrupted to enable a tramper to press the fiber into the box to make room for more from the feed. After each tramping, dogs in the sides of the bale box engage the mass of fiber and keep it more-or-less in the tramped configuration.
When the bale box has been filled with tramped fiber, it is usually rotated to a second position while another box replaces it so that the feeding and tramping operation can continue. The fiber in the original bale box, in its new position, is then further compressed into the final bale form. Generally this is accomplished by an hydraulic ram which, in the more common instances, presses up from the bottom of the bale, or in some cases may press down from the top. Since the horizontal cross-section of the bale box is usually about two feet by four and one-half feet, and since it may be desirable to achieve densities of from ten to thiry pounds per cubic foot of fiber, considerable hydraulic pressure is required, and very heavy, expensive presses are needed to achieve densities of more than about eighteen pounds per cubic foot.
In many cases the volume of production does not justify the cost of the heavy presses needed to achieve the customary densities of about 20 to 22 pounds per cubic foot used for shipping bales to domestic mills, or the even higher densities of 30 to 32 pounds per cubic foot employed in shipping cotton to overseas mills. To achieve these higher densities, bales from the gin, which are usually called "bin bales" or "flat bales", are shipped to compress companies where they are recompressed to the higher densities of very heavy steam-actuated compress machines.
In some instances bales which have been compressed a second time to 20 to 22 pounds for domestic shipment are pressed a third time to 30 to 32 pounds if their destination has been changed to that of an overseas mill.
The recompression of bales necessitates replacement of the steel bale bands or ties, as well as labor and handling charges. Occasionally, the covering material, such as jute or burlap, must also be replaced. All this adds to cost and inefficiency.
Bales or packages of cotton usually weigh between about four hundred and seven hundred pounds, with the average weight being in the range of five hundred to five hundred fifty pounds. When such a mass of fibers is compressed with conventional equipment, each individual fiber must be displaced or deformed, and this in turn brings into play various forces that resist the compression, including inter-fiber friction and resistance to bending, stretching, and torsional deformation. The sum of these forces from hundreds of millions of fibers must be overcome, and in addition air entrapped between the fibers must either be expelled or compressed. These factors together account for the very high pressures and heavy equipment which must be employed in conventional methods of packaging and compression of bales of cotton. The cross-sectional area upon which pressure is applied may approximate 1,400 square inches, and the hydraulic pressure in the ram cylinder may have to be as high as 3,000 pounds per square inch. This in turn means that higher capacity, more expensive pumps, requiring as high as one hundred horsepower motors must be employed.
The resulting high cost of equipment for conventional presses, with automatic strapping severly limits their usefulness.
The present invention embodies a recognition that if the amount of fiber to be compressed at any one time can be sharply reduced, and if the pressure can be applied over a much smaller area, the forces necessary for compression are greatly reduced.
That principle has been adopted experimentally in the production of round bales of cotton where a batt of cotton is passed between squeeze rolls and, upon emerging, is formed into a cylinder-shaped roll, aided by the use of additional rollers to retain the compression imparted by the original pair of "squeeze rolls." However, round bales are not generally acceptable to textile mills since they cannot be packed and shipped as efficiently as rectilinear bales or packages, and they are more difficult to handle during warehousing and processing.
A variety of prior proposals have contemplated the formation of rectilinear type cotton bales through the application of pressure over the area of successive cotton layers. Such proposals may not be entirely acceptable for a variety of reasons.
For example, relative movement between the bale and compression roller assemblies during bale formation may involve a significant amount of undesirable power losses attributable to the recompression of cotton in a given layer. In this connection, it will be appreciated that during relative movement between the cotton layer and the rollers, the cotton compressed by each roller sequentially expands toward the interstices between adjacent rollers and is recompressed by the next roller. This may tend to occur despite the inclusion of belts or the like around the roller assemblies.
Other proposals appear to avoid the losses associated with relative translation between the cotton and the compression elements through the use of compression elements carried as part of a chain assembly.
However, such proposals require complex mechanisms for the mounting of the compression elements and for the maintenance of pressure on the cotton through those compression elements, which mechanisms may not provide adequate support from the standpoint of mounting compression elements to withstand the high pressures involved.
Moreover, those proposals might involve a significant amount of undesirable power losses by reason of reciprocation of either the support for the bale or the support for the chain assembly during bale formation. In this regard, it will be apparent that such proposals might also present significant problems in relation to removal of the completed cotton bale for packaging while maintaining that bale in a compressed condition.
Other difficulties associated with prior proposals designed to form cotton bales through application of pressure over smaller areas of cotton layers may be envisioned.